The development of smaller, highly sophisticated consumer electronics has increased demands for compact and low-profiled semiconductor chips used in consumer electronic devices correspondingly. To accommodate this increase in demand, a connection method to connect a semiconductor chip and the substrate in the semiconductor device has been developed which is referred to as flip chip bonding. In traditional wire bonding techniques, the chip and the substrate are connected by wires, with a surface of the chip facing upwards, upon which connection terminals are provided. With flip chip bonding, protruding connection terminals referred to as “bumps” are provided on the chip. The chip is reversed (flipped) so that the bumps are on the lower surface and are thus directly connected to the substrate.
With flip chip bonding, the area at the bump periphery between the chip and the substrate is filled with a thermo-setting resin referred to as “underfill” for reinforcement. However, mounting using flip chip bonding poses a problem that this underfill material would often crawl up. This is depicted with reference to FIG. 1. FIG. 1 shows one example of mounting using flip chip bonding. As shown in FIG. 1, the front surface (circuit forming surface) 11 of chip 1 functions as the lower surface, while the back surface (surface opposite the circuit forming surface) 12 of chip 1 functions as the upper surface. Bumps 2 are arrayed on a front surface 11 of chip 1. The circuit formed in chip 1 and the circuit of the substrate 3 are connected through bumps 2.
When mounting chip 1 onto the substrate 3, an underfill 4 is coated in advance at locations where chip 1 is to be fixed to the substrate 3, for instance. Chip 1 is picked up by a bonding head 5 and is mounted at the fixing location of chip 1 on the substrate 3 onto which the underfill 4 is coated. Then, pressure and heat are applied from above by the bonding head 5. As a result, the underfill 4—which is typically a thermo-setting resin—cures, thereby fixing the chip 1 to substrate 3.
If the coated amount of underfill 4 is small, there is a risk that the underfill 4 will not sufficiently reach the periphery of bumps 2. This means that the underfill 4 must be coated in larger amounts to a certain degree. On the other hand, if the underfill 4 is coated in large amounts, the excess underfill 4 sticks out at the periphery of chip 1. The part of underfill 4 that sticks out is referred to as a “fillet portion.” If the volume of the fillet portion is large, the underfill 4 may rise and coat the side surface(s) of chip 1 as shown in FIG. 1 and adhere to the bonding head 5.
If the underfill 4 adheres to the bonding head 5, the chip 1 may be lifted to some degree, thereby causing shearing to occur in bumps 2 when the bonding head 5 is pulled up after mounting is completed. Furthermore, the underfill 4 that adhered cures and damages the flatness of the bonding head 5, thereby causing a drop in the quality of flip chip products.
FIG. 2 discloses a conventional technique to solve the problems caused by the underfill 4 rising up.
However, in conventional techniques for preventing the rise and coating of the underfill 4, the peripheral edge of the front surface 11 of chip 1 is removed to provide a ledge at the periphery of the front surface 11. This ledge prevents the underfill 4 from rising up and coating the side surface of the chip 1.
However, the fillet portion of the underfill 4 may exceed the ledge formed at the periphery of the front surface 11 of chip 1. The ledge formed at the periphery of the front surface 11 of chip 1 may therefore be insufficient with respect to the volume of the fillet portion, thereby creating a problem that coating of the side surfaces of the chip 1 cannot be prevented.